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1

Analysis of application of gradient concrete models to assess concrete cover degradation under reinforcement corrosion

Yurkova Kseniya, Krykowski Tomasz

Architecture Civil Engineering Environment

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2023

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Vol. 16, no. 4

109--123

EN

The paper presents a comparative analysis of the application of two nonlocal gradient-formulated models to evaluate the concrete cover degradation time. Calculations were made taking into account the increase in the volume of the steel ring around the perimeter of the reinforcement bar. The results of the calculations were compared with the results of experimental studies published in the literature and with the elastic-plastic model based on the Menetrey-Willam surface, in which the objectivity of the obtained results depends on the fracture energy. In addition, the paper compares solutions using different contact models and cohesion models.

2

Effect of simulated axial residual stress and transverse residual stress in welded P92 pipe and plates including plasticity error

Pal Vinay Kumar, Singh Lokendra Pal

Journal of Mechanical and Energy Engineering

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2022

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Vol. 6, No 2

1--18

EN

The paper deals with the measurement of residual stresses in P92 welded pipe using the blind hole drilling technique. The post weld heat treatment (PWHT) of a P92 welded pipe was also conducted to study their effect on residual stresses. The P92 pipe weld joints were prepared using gas tungsten arc welding process. The residual stress measurement was carried out using a strain gauge rosette that was associated with the plastic deformation of the material and a stress concentration effect of a multi-point cutting tool. A corrective formulation was developed for calculating the corrected value of residual stresses from the experimentally obtained strain value. The Strain gauge response was estimated experimentally using tensile testing for uniaxial loading while a finite element analysis was performed for biaxial loading. A gas tungsten arc welds joint was prepared for a conventional V-groove and a narrow groove design.

3

Feasible brittleness evaluation method and suggestion for brittleness reduction of cementitious materials based on stress–strain curve

Fu Qiang, Wang Zhenhua, Zhou Zhiming, Niu Ditao, Wang Yan

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e209, 2022

EN

In this study, a brittleness evaluation index B5 and brittleness–plasticity classification standard for cementitious materials were established, and a suggestion for brittleness reduction was proposed. The results showed that B5 established based on the principle of energy conversion can effectively characterize the variation in the brittleness of cementitious materials with the confining pressure, and the brittleness order of different cementitious materials. Based on the established brittleness–plasticity classification standard, the ranges of B5 corresponding to the weak, high and ideal brittleness are [0.3, 0.6), [0.6, 1) and 1, respectively; and those corresponding to the weak, high and ideal plasticity are [0.1, 0.3), (0, 0.1) and 0, respectively. Finally, a suggestion for brittleness reduction using prismatic aggregates and hybrid nanofibers, flexible and rigid fibers of different sizes was proposed, and the corresponding design process of cementitious materials with weak brittleness was given. The research results in this study provide a basis for the brittleness evaluation of cementitious materials and the design of cementitious materials with weak brittleness.

4

A successive approximation method for thermo-elasto-plastic analysis of a reinforced functionally graded rotating disc

Kholdi Mohsen, Saeedi Soheil, Moradi Sayed Ali Zargar, Loghman Abbas, Arefi Mohammad

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no e2, 2022

EN

Thermo-elasto-plastic analysis of a rotating disc made of Functionally Graded Materials (FGMs) is studied in this paper using Successive Approximation Method (SAM). The plane stress condition is assumed for formulation of the problem. After computation of effective material properties based on modified mixture rule, the governing equations are derived analytically and then is solved using the Differential Quadratic Method (DQM). After obtaining the displacements and stresses, the yield conditions are calculated by von-Mises failure criteria. The rotating disc is made of an Aluminum–Silicon Carbide functionally graded material. The plastic behavior of Aluminum is considered as strain hardening one. The effects of angular speed, percentage of ceramic particles, particle reinforcement power, and boundary conditions such as temperature gradient on the radial and tangential thermo-elasto-plastic strains, stresses, and equivalent stresses is investigated. The results show that the radial stresses through the disc are significantly less than tangential stresses, therefor the tangential stresses has a significant effect on the equivalent stress and yield conditions.

5

Wpływ wielkości i kształtu kruszywa na wytrzymałość betonu na ściskanie i plastyczność

Darvishvand Hamid Reza, Haj Seiyed Taghia Seiyed Ali, Ebrahimi Masood

Cement Wapno Beton

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2021

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R. 26, nr 1

46--54

PL

Zagadnienie wielkości i kształtu kruszywa w betonie dla osiągnięcia maksymalnej wytrzymałości i plastyczności, jest jednym z ważniejszych zagadnień w budownictwie. Do zbadania tych właściwości wybrano dwa rodzaje kruszywa o czterech uziarnieniach. Pierwszym kruszywem był żwir o zaokrąglonych ziarnach zaś drugim grys o ziarnach ostrokrawędzistych. Maksymalne wymiary ziaren wynosiły dla obu kruszyw odpowiednio 9,5, 12,5, 19 i 25 mm. Dobrano zawartość cementu 250, 350, 450 i 550 kg/m3 oraz stosunek wody do cementu równy 0,4. W pierwszej kolejności wykonano badania wytrzymałości na ściskanie oraz odkształcalności próbek. Zgodnie z wynikami badań, wytrzymałość na ściskanie wzrastała wraz ze wzrostem zawartości cementu, co jest zgodne z oczekiwaniami. Beton z kruszywa o maksymalnej wielkości ziaren wynoszącej 12,5 mm ma największą wytrzymałość na ściskanie i plastyczność w porównaniu z innymi uziarnieniami i zostało wybrane jako optymalne, a betony z kruszywa ostrokrawędziste mają większą wytrzymałość na ściskanie i plastyczność w porównaniu z betonami z kruszyw o zaokrąglonych ziarnach.

EN

The issue of the size and shape of the aggregates in concrete is one of the most challenging subjects in the building industry, in order to reach maximum strength and ductility. To investigate this issue, two types of aggregate were selected. One was the river aggregate - gravel with rounded grains and the second was a crushed stone with sharp-edged grains, both with the maximum sizes of 9.5, 12.5, 19, and 25 mm respectively. The cement content was 250, 350, 450, and 550 kg/m3, and the water to cement ratio was equal to 0.4. At first, the compressive strength and stress-strain relationship were examined. According to the test results, the compressive strength increases with increasing cement content, as expected. The aggregate with the largest grain size of 12.5 mm gives the highest compressive strength and ductility compared to other grain sizes and it was selected as the optimal choice and finally, the sharp-edged aggregates have higher compressive strength and ductility in comparing to the rounded grain aggregates.

6

Development of new fully restrained bolted bracket moment connections for strong joints

Ghobadi Mohammad Soheil, Abar Bahram Mirzaie

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

159--188

EN

Recently, the Double Shear Bolted Brackets (DSBB) moment connection with four-bolt configuration has been introduced as a new fully restrained moment connection for use in shallow beam-column joints. With regards to deep beam connections, it is a requirement to have stiffer and stronger connections in the DSBB connection group. Knowing that similar code-qualified bolted bracket connections, Kaiser Bolted Bracket (KBB) connections, have marginal rotational stiffness, they cannot be considered as a fully restraint moment connection in deep beam-to-column joints. Therefore, in this discourse, six-bolt and eight-bolt configurations of DSBB are developed and their design methodology is outlined. Less thickness of bracket components, less diameter of bolts used, and greater stiffness compared to KBB code-qualified (AISC 358-16 standard) connections by the (KBB connection) are the main advantages of these new connections, making them a more applicable option of fully restrained connections for deep beam joints than their counterpart KBB connection. First, the DSBB design method is developed considering all possible limit states of buckling, yield, and rupture failures for the plate components of each bracket. Then, by using a validated high fidelity finite element study, the cyclic performance of DSBB connections is obtained and successfully accepted based on the AISC 341-16 standard requirements for fully restrained connections in special moment connections. The results indicated the low risk of failure and proper relaxed stress distribution around the connection compared to the corresponding KBB connection. In addition, the material consumption of DSBB six-bolt and eight-bolts were 19.7% and 6.9% in bolts and were 19.9% and 42.9% in brackets less than that of the corresponding KBB connections. Finally, it is concluded that DSBB six-bolt and eight-bolt configurations are efficient choices of fully restrained moment connections for application in deep beam-column joints.

7

Compressive properties, mechanical anisotropy and hardness analysis of Mg-Zn alloy under cross pre-compression

Long Jianyu, Nazeer Faisal, Yang Zhe, Li Chuan

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

355--367

EN

The Mg–6Zn wt.% (MZ-T6) magnesium (Mg) alloy was fabricated after heat treatment (783 K for 6 h and aging at 453 K for 24 h) of an extruded MZ Mg alloy. Later, the alloy was subjected to cross pre-compression along with different directions and strains and obtained MZ-1 and MZ-2Mg specimens. The MZ-1 was pre-compressed along with ED and then TD, whilst MZ-2 was pre-compressed along with ND and TD. Subsequently, the compressive properties were studied of MZ-T6, MZ-1, and MZ-2 specimens. The result displayed that the cross twinning and lenticular twinning significantly altered the < c > axis orientations from c-axes || normal direction (ND) of MZ-T6 Mg specimen towards c-axes || extruded direction (ED) and transverse direction (TD) in MZ-1 and MZ-2Mg specimens, respectively. The compressive yield strength and ultimate compressive strength were significantly increased along with all loading directions, and mechanical anisotropy was significantly reduced. These results are mainly attributed to twin-induced grain refinement and considerable changes in the texture. The concave down curves changed to sigmoidal curves in pre-compressed Mg specimens along with ND, which is the signature of the twinning and de-twinning phenomenon. While loading along ED and TD exhibited almost similar sigmoidal curves in all specimens, however, the curves displayed different deformation behavior and were evaluated based on strain hardening regimes. The hardness of MZ-1 and MZ-2 specimens was increased ~ 18 and ~ 23%, respectively, compared to the MZ-T6 specimen. Thus, cross pre-compression is a convenient technique to further enhance the applications of Mg alloys for industrial development.

8

Seismic strengthening of nonductile bridge piers using low-cost glass fiber polymers

Rodsin K., Hussain Q., Joyklad P., Nawaz A., Fazliani H.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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Vol. 68, nr 6

1457--1470

EN

Several recent earthquakes have indicated that the design and construction of bridges based on former seismic design provisions are susceptible to fatal collapse triggered by the failure of reinforced concrete columns. This paper incorporates an experimental investigation into the seismic response of nonductile bridge piers strengthened with low-cost glass fiber reinforced polymers (LC-GFRP). Three full-scale bridge piers were tested under lateral cyclic loading. A control bridge pier was tested in the as-built condition and the other two bridge piers were experimentally tested after strengthening them with LC-GFRP jacketing. The LC-GFRP strengthening was performed using two different configurations. The control bridge pier showed poor seismic response with the progress of significant cracks at very low drift levels. Test results indicated the efficiency of the tested strengthening configurations to improve the performance of the strengthened bridge piers including crack pattern, yield, and ultimate cyclic load capacities, ductility ratio, dissipated energy capacity, initial stiffness degradation, and fracture mode.

9

Analysis of composite shear walls with a gap between reinforced concrete wall and steel frame

Bahrami Alireza, Yavari Mojtaba

Archives of Civil Engineering

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2020

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Vol. 66, nr 1

41--53

EN

In this research, nonlinear analysis of composite shear walls (CSWs) with a gap between reinforced concrete wall and steel frame is investigated under cyclic loading by the use of the finite element method (FEM) software ABAQUS. For the purpose of the verification, an experimental test is modelled and comparison of its obtained result with that of the experimental test demonstrates an inconsiderable difference between them; therefore, the reasonable accuracy of the modelling is revealed. Then, effects of different parameters on the behaviour of the CSWs are examined. Gap size between reinforced concrete wall and steel frame, reinforcement percentage, steel sections of beams and columns, and existence of reinforced concrete wall are considered as parameters. It is concluded that change of the parameters affects the ultimate strength, ductility, and energy dissipation of the system. A steel shear wall (SSW) is also modelled and compared with the CSWs. Buckling of the walls is presented as well.

10

Application of nanoindentation to evaluate the hardness and yield strength of brass joints produced by FSW: microstructural and strengthening mechanisms

Heidarzadeh A., Paidar M., Güleryüz G., Barenji R. Vatankhah

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 2

158--166

EN

Nanoindentation test was employed to measure the actual hardness and yield strength of the stir zone in the friction stir-welded single-phase brass joints. For this aim, different joints were prepared according to an experimental matrix based on the central composite rotatable design. In this design matrix, the tool rotational speed, tool traverse speed, and tool axial force were the input parameters. The outputs were the hardness and yield strength of the joints. To measure the hardness and tensile strength of the joints, the nanoindentation test was employed. Moreover, electron back scattered diffraction and transmission electron microscopy techniques were used to study the microstructural features. The results showed that by decreasing rotational speed and axial force, and by increasing the traverse speed, the hardness and yield strength of the joints were increased. In other words, lower heat inputs caused higher strength in the joints. Finer grain sizes, larger grain average misorientation amounts, i.e., existence of more dislocations, and greater Taylor factors in the lower heat input joints revealed that the influence of grain boundaries, dislocations, and texture were the origins of better mechanical properties.

11

Mikrostruktura i właściwości mechaniczne połączeń spawanych stali nierdzewnych austenitycznych

Tuz Lechosław

Spajanie Materiałów Konstrukcyjnych

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2019

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Nr 4 (46)

22--24

PL

Zastosowanie stali austenitycznych w różnych gałęziach przemysłu ciągle wzrasta, co wynika z ich unikalnych właściwości mechanicznych, plastyczności i odporności na korozję. Powoduje to, że w środowisku agresywnym uzyskuje się wysoką trwałość przez wiele lat i możliwość ograniczenia ciężaru wyrobu.

12

Peculiarities of Alloying Effect on the Eutectic Cementite Behavior Under Hot Rolling

Mironova Tatiana, Proidak Svetlana

New Trends in Production Engineering

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2019

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Vol. 2, Iss. 2

289-300

EN

Currently, cast iron remains one of the major modern casting materials in metallurgy and machine-building industry and is sure to take the lead in the future. Chilled cast iron has high hardness and wear resistance due to a large number of carbide phases in its structure. However, low ductility and impact hardness essentially limit its applicability in terms of processing. Hot plastic working, under which the eutectic net crushing is observed, appears to be one of the most effective means of the eutectic alloy products shape and microstructure transformation. Chilled cast iron properties fundamentally improve after hot plastic working: ductility, strength and impact hardness increase by 2-3 times on retention of the high hardness factor. Chilled cast iron ductility increase can be attained when using phase transformations in eutectic cementite under lean alloying with carbide forming elements. The purpose of the paper is to study alloying effect on the chilled cast iron ductility as well as eutectic cementite behavior under hot rolling. In the paper hardening and softening of the structural components in chilled cast iron under hot working have been studied. The deformation texture forming in eutectic cementite under hot rolling has been revealed, which is connected with the dynamic softening and depends on the degree and the nature of its alloying. The mechanism and regularities of the phase transformation effect in cementite on its behavior under plastic deformation and on the alloys ductility in general have been studied. In cementite chromium alloying initiates processes, that can be characterized as the pre-precipitation stage of the new phases, and this way it contributes to the cast iron ductility reduction and embrittles cementite. Carbide transformation, that occurs in eutectic cementite under alloying with vanadium, stimulates softening of the alloy and increases its ductility level. Moreover, the multiple glide planes {130},{011},{112} in cementite have been determined. It has been found out, that in supersaturated cementite vanadium carbides precipitation stimulates the extra glide plane {111} occurrence under hot rolling. The essence of the carbide transformation phenomenon is that under hot working there occurs the lubricating effect at the transition of the metastable iron carbide condition, which is strengthened with vanadium supersaturation and mechanical hardening, to a more stable condition due to precipitation of the proeutectoid constituents on the one hand, and because of the dynamic softening processes on the other hand. At that, the autocatalyticity effect is observed: there is precipitation of carbides with hardening and softening, similar to the processes that arise as a result of the superplastic effect induced by phase transformations.

13

Dieless drawing process for elongation of thin copper and copper alloy wire

Milenin Andrij, Kustra Piotr, Wróbel Mirosław, Pidvysots’kyy Valeriy, Paćko Marek

Journal of Metallic Materials

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2019

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Vol. 71, no. 3

12--15

EN

The article proposes a new process for the production of thin wires made of copper and copper alloys. The proposed process is based on the idea of dieless drawing. The workpiece for dieless drawing is a thin wire obtained through a conventional drawing method. The proposed technology is based on a multi-pass process. The deformation parameters in each pass are determined on the basis of an analysis of the dependence of the flow stress of the material on the strain, strain rate and temperature. For this purpose, plastometric tests of a copper and CuZn37 alloy were performed. In order to determine technological plasticity and roughness propagation during dieless drawing, physical and numerical modelling of this process were performed. The obtained data were used in the practical implementation of the dieless drawing technology.

PL

Artykuł poświęcono nowemu procesowi produkcji cienkich drutów z miedzi i jej stopów. Zaproponowany proces jest oparty o idee ciągnienia bezmatrycowego. Wsadem do ciągnienia bezmatrycowego jest cienki drut, wyprodukowany za pomocą metody konwencjonalnego ciągnienia. Proponowana technologia jest oparta na wieloprzepustowym procesie. Parametry odkształcenia w każdym przepuście są wyznaczane na podstawie analizy zależności naprężenia uplastyczniającego od odkształcenia, prędkości odkształcenia i temperatury. W tym celu przeprowadzono badania plastometryczne miedzi i stopu CuZn37. Celem wyznaczenia technologicznej plastyczności oraz propagacji chropowatości powierzchni drutu w trakcie ciągnienia bezmatrycowego wykonano fizyczne i numeryczne modelowanie procesu. Otrzymane dane wykorzystano podczas praktycznej implementacji procesu ciągnienia bezmatrycowego.

14

Research of the dual phase steel DP450 properties from the forming aspects

Bilik Jozef, Tittel Viktor, Sobota Robert, Suba Roland

Hutnik, Wiadomości Hutnicze

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2019

|

Vol. 86, nr 1

14--17

EN

The paper is focused on study of plasticity and formability of dual phase steel DP 450, which is used in automotive industry. The paper shows results from tensile test for plasticity determination and also results of technological tests for complex evaluation of formability. These consisted from Erichsen cup test, Fukui test and Schmidt test. The paper shows also results of microhardness measurement.

PL

Artykuł koncentruje się na badaniu plastyczności i odkształcalności stali dwufazowej DP 450, która jest stosowana w przemyśle motoryzacyjnym. W pracy przedstawiono wyniki prób rozciągania dla określenia plastyczności, a także wyniki testów technologicznych dla kompleksowej oceny odkształcalności. Składały się one z testu pucharowego Erichsena, testu Fukui i testu Schmidta. W pracy przedstawiono również wyniki pomiaru mikrotwardości.

15

Some geotechnical properties of pure and waste gypsum for geoelectrical grounding applications

Mohd Tadza Mohd Yuhyi, Mazelan Nurmazuria, Yusri Nur Farahana, Abdullah Amizatulhani

Civil and Environmental Engineering Reports

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2019

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Vol. 29, no. 3

97--106

EN

Natural occurring gypsum is a soft mineral consists of hydrated calcium sulphate, mainly used in cement industry. On the other hand, red gypsum (RG) is a waste generated from a sulphate process of ilmenite ore to acquire titanium dioxide. Due to the gypsum content in both materials are similar, it is expected that both gypsum type can be used for similar engineering applications. In this study, RG was tested and compared to pure gypsum for geoelectrical grounding applications. The geotechnical properties and plasticity characteristics were carefully measured and tested. In addition, X-ray fluorescence (XRF) was employed to study the chemical constituents of the materials. Test results showed that, the geotechnical properties of RG is different to that of white gypsum. The plasticity index (PI) of RG was 239.6% greater due to the presence of Fe ions. Surprisingly, the electrical resistivity of both material were found to be similar. It was also noted that, although the plasticity of pure gypsum is high, the plasticity of pure gypsum was found to be short lived primarily due to instantaneous exothermic reaction between water and semihydrated gypsum. The change in the plasticity also affected the resistivity as gypsum hardened after short duration. Based on the geotechnical and plasticity characteristics determined, RG was found to be a better as grounding material as compared to gypsum.

16

Plasticity and swell-shrink behaviour of electrokinetically stabilized virgin expansive soil using calcium hydroxide and calcium chloride solutions as cationic fluids

James Jijo, James Archana, Kumar Arun, Gomathi Elumalai, Prasath Karunakaran Kamal

Civil and Environmental Engineering Reports

|

2019

|

Vol. 29, no. 1

128--146

EN

This investigation focussed on the plasticity and swell-shrink behaviour of an expansive soil that was stabilized using electro kinetic stabilization (EKS) techniques with cationic fluids for enhancement of stabilization. 0.25 M solutions of calcium hydroxide and calcium chloride were used as cationic fluids. An electro kinetic (EK) cell of dimensions 500 mm x 150 mm x 160 mm with inert graphite electrodes of size 140 mm x 160 mm x 5 mm was adopted for the stabilization process, carried out at an applied voltage of 40 V over a period of 6 hours. After the duration of the test, stabilized soil sample was subjected to Atterberg limits and free swell tests to determine its plasticity and swell-shrink characteristics. The results of the investigation found that both fluids were capable of reducing the plasticity and swell-shrink behaviour of the soil with different levels of effectiveness.

PL

W badaniach skupiono się na plastyczności i kurczeniu się gleby, która została ustabilizowana za pomocą technik stabilizacji elektrokinetycznej (EKS) z płynami kationowymi. Jako płyny kationowe stosowano 0,25 M roztwory wodorotlenku wapnia i chlorku wapnia. Do procesu stabilizacji przyjęto ogniwo elektrokinetyczne (EK) o wymiarach 500 mm x 150 mm x 160 mm z obojętnymi elektrodami grafitowymi o wymiarach 140 mm x 160 mm x 5 mm, przy zastosowaniu napięcia 40 V przez okres 6 godzin. Po zakończeniu testu stabilizowaną próbkę gleby poddano testom Atterberga i badaniom swobodnego spęcznienia w celu określenia jego plastyczności i charakterystyki kurczenia się. Wyniki badania wykazały, że oba płyny były w stanie zmniejszyć plastyczność i kurczenie się gleby przy różnych poziomach skuteczności.

17

Role of dilatancy angle in plasticity-based models of concrete

Wosatko Adam, Winnicki Andrzej, Polak Maria Anna, Pamin Jerzy

Archives of Civil and Mechanical Engineering

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2019

|

Vol. 19, no. 4

1268--1283

EN

The so-called concrete damaged plasticity (CDP) model is frequently employed by ABAQUS users to simulate the behaviour of concrete. One important aspect of the model, namely the representation of material dilatancy, is evaluated in the paper. The role of the dilatancy angle in pressure-dependent plasticity models is reviewed. The plastic potential adopted in the CDP model is discussed. It is shown that the definitions of the angle in the CDP model and in the Burzynski–Drucker–Prager (BDP) plasticity model for a continuum can lead to different angle magnitudes. Two tests on concrete configurations are simulated to illustrate how strongly the angle influences the results: the Kupfer benchmark of a panel under uniaxial or biaxial compression and the punching shear response in a slab-column connection. The importance of viscosity in cracking simulation is thereby mentioned, the results are compared with experimental ones and mesh sensitivity is verified. Recommendations for analysis of concrete mechanics problems are formulated.

18

Adaptive Plasticity in Insect Parasites – Philopterus Lice and their Accentor Passerine Hosts

Janiga M.

Polish Journal of Ecology

|

2018

|

Vol. 66, nr 4

395--406

EN

One hundred and five alpine accentors Prunella collaris (Scopoli, 1786) and ninety four dunnocks Prunella modularis (Linnaeus, 1758) were captured in the West Carpathian Mountains of Slovakia in order to compare the morphology of their Ischnoceran parasites Philopterus emiliae Balát 1985 and Philopterus modularis (Denny, 1842), respectively. In the case of both host species, the largest bodied lice occurred in winter, before the beginning of the host breeding season. Lice collected during the host breeding season were smaller in size than those collected in winter. Lice collected in the autumn, following postnuptial molt were even smaller in size. The largest lice were found on the bodies of host individuals with relatively long wings. The lice Ph. emiliae also differed in shape. In winter, the relative size of the head was large, while in the autumn, the head was proportionately smaller in size, compared to other body regions. Adult lice Ph. modularis also tended to have larger heads in April than in July. Measurements of lice over an eleven year period from the same site yielded differences in shape, but not in size. This study is one of the first assessments of seasonal variation in morphology of lice.

19

Wymagania materiałowe dla stali zbrojeniowej według obowiązujących norm w kontekście projektowania mostów

Piotrowska M.

Mosty

|

2018

|

nr 3/4

60--62

PL

W zakresie produkcji stali zbrojeniowej od czasów ostatnich aktualizacji norm PN-B i PN-S do projektowania konstrukcji dokonał się olbrzymi postęp, oferta rynkowa hut stali jest obecnie znacznie bogatsza, a wyroby mają o wiele wyższą jakość. Warto mieć prawidłowe rozeznanie i wiedzieć, na jakie parametry stali poza wytrzymałością na rozciąganie należy zwrócić uwagę, aby zapewnić maksymalne bezpieczeństwo konstrukcji.

EN

The choice of steel for reinforced concrete bridges in Poland is very often limited to the A-IIIN class, which is consistent with the „old” Polish design standards, that are still widely used. Such clauses are notoriously appearing in technical specifications for many bridges in Poland. Recommendations of the grades of steel occur as well, often of the ones currently unavailable on the market – although they are also in line with the „old” standards. Since the recent revision of the PN-B and PN-S standards for structural design, steelmaking has made tremendous progress, and products are of a much higher quality. It is recommended to have a proper view and know what parameters, apart from the tensile strength, are worth to pay attention to, in order to ensure the maximum structure safety.

20

The sigma phase precipitation during high temperature deformation of the X2CrNiMoN25-7-4 duplex steel

Stradomski G., Jasińska J., Laber K., Sawicki S.

Hutnik, Wiadomości Hutnicze

|

2018

|

Vol. 85, nr 2

54--57

EN

Steels and other ferrous alloys are very well known as construction materials and still are widely used and in the near future this will not change. Duplex steels due to the two-phase construction combine high corrosion resistance and good mechanical properties. Both those parameters are at higher level than austenitic stainless steels and that why duplex steels are irreplaceable material in many fields like the petrochemical, power, pulp and paper, and food industry. This multiphase microstructure generates a lot of problems which have already been repeatedly presented in many works. Among the steels and cast steels resistant to corrosion most modern and dynamically developing group are ferritic-austenitic alloys, commonly known as duplex. The chemical composition of a steel containing about 0.02% C, 26% Cr, 6.5% Ni, 3% Mo, 1.4% Mn, 0.2% N guarantees that already after casting is obtained ferritic - austenitic structure. The paper present results of the X2CrNiMoN25-7-4 duplex steel physical tests made with the Gleeble 3800 machine. The research concerns problems of the influence of primary structure on the plasticity and sigma phase formation.

PL

Stale obok innych stopów żelaza są dobrze znanymi, szeroko wykorzystywanymi materiałami konstrukcyjnymi i sytuacja taka w najbliższej przyszłości nie ulegnie zmianie. Stale dupleks dzięki swojej dwufazowej budowie cechuje wysoka odporność korozyjna oraz wysokie właściwości mechaniczne. Obydwa te parametry są na wyższym poziomie niż stali austenitycznych i dlatego stale dupleks są niezastąpionym materiałem w wielu gałęziach przemysłu jak petrochemiczny, energetyczny, papierniczy czy w produkcji żywności. Taka budowa mikrostruktury powoduje pojawienie się wielu problemów, które już w wielu pracach były szeroko omawiane. Wśród stali i staliwa odpornego na korozję najszybciej rozwijającą się grupą są stopy ferrytyczno-austenityczne znane również jako dupleks. Skład chemiczny stali zawierającej 0,02% C, 26% Cr, 6,5% Ni, 3% Mo, 1,4% Mn, 0,2% N gwarantuje uzyskanie już w stanie lanym mikrostruktury ferrytyczno-austenitycznej. W pracy przedstawiono wyniki badań fizycznych przeprowadzonych z wykorzystaniem urządzenia Gleeble 3800 na stali X2CrNiMoN25-7-4. Badania dotyczą problemów wpływu mikrostruktury pierwotnej na plastyczność oraz wydzielanie się fazy sigma.